docs: def load_subset(corpus, path, subset_idx):
          """ Load subset into corpus. """
          csv_file = os.path.join(path, '{}.tsv'.format(subset_idx))
          subset_utt_ids = []
  
          entries = textfile.read_separated_lines_generator(
              csv_file,
              separator='\t',
              max_columns=8,
              ignore_lines_starting_with=['client_id'],
              keep_empty=True
          )
  
          for entry in entries:
  
              file_idx = CommonVoiceReader.create_assets_if_needed(
                  corpus,
                  path,
                  entry
              )
              subset_utt_ids.append(file_idx)
  
          filter = subset.MatchingUtteranceIdxFilter(utterance_idxs=set(subset_utt_ids))
          subview = subset.Subview(corpus, filter_criteria=[filter])
          corpus.import_subview(subset_idx, subview)